WD 40 works for its intended purpose
My brother's firearms were damaged by saltwater when his home was flooded by hurricane Sandy. Aside from immediate assistance to stabilize the damage to his home, we bought a bottle of WD 40 and sprayed every surface and seam on his firearms as soon as possible. This was done to displace saltwater and halt corrosion.
After a few months I was able begin cleaning and repairing his firearms. WD 40 worked as advertised. The WD 40 residue is waxy and protective but not a lubricant applicable to firearms. Cleaning has been easy and, despite some corrosion. the rescued firearms are slowly recovering. The remediated firearms are properly lubricated with white lithium, Mobil 1, and Breakfree CLP. WD 40 did its job.